The present invention relates to a method for the preparation of N-glycolyl neuraminic acid. More particularly, the invention relates to an efficient and economical method for the preparation of N-glycolyl neuraminic acid from an inexpensive raw material of good availability as a hardly disposable waste material of nuisance discharged from fishery.
Acyl derivatives of neuraminic acid, having a generic name of sialic acids, are found at the non-reducing terminals of the molecules of certain complex saccharide compounds and play an important physiological role in living bodies. About 20 kinds of different sialic acids are known including those of which the N-acyl group is an N-acetyl group or N-glycolyl group and those of which the hydroxyl groups are substituted by acetyl groups or methyl groups.
According to the recent discovery relative to these sialic acids, N-glycolyl neuraminic acid is found in the living cells of human colorectal cancers and breast cancers though in a very small amount so that this compound is now becoming interested as a cancer marker.
It is the prior art that N-glycolyl neuraminic acid, which is used as a reference reagent in the analysis of saccharide compositions of a complex saccharide, is prepared by isolating and recovering from the tissues of vertebrate animals such as horses, cattle, pigs, dogs and the like. A problem in this supply route of the source material for the compound is that the content thereof in the living body tissues of the vertebrate animals is low and, in addition, difficulties are encountered in the purification of the compound isolated from the living body tissues necessarily leading to expensiveness of the commercial product. Moreover, the purity of the commercially available products of N-glycolyl neuraminic acid can hardly be higher than about 90% .
The inventors have conducted extensive investigations with an object to develop a novel and economical route for supplying N-glycolyl neuraminic acid including screening works to uncover a promising source material of the compound which can replace the vertebrate tissues, which have been the only source material of the compound in the prior art, and, directing their attention to a variety of materials occurring in nature, they have arrived at an unexpected discovery that certain marine animals well meet this purpose leading to establishment of the present invention after detailed studies on the processing procedure of the source material.